In the field of structures or in the field of mechanics in general, it is known to assemble several pieces by means of fasteners, rivets or bolts for example, passing through a pre-formed hole and running through the pieces to be assembled.
In many cases it is necessary to obtain a perfect alignment of the hole running through the various pieces and to produce the hole in the various pieces while they are in the relative positions they must occupy during assembly.
When the various pieces are composed of materials that are similar in nature, a metal alloy such as steel or an aluminum alloy for example, the drilling does not present any particular problem in terms of the cutting tool chosen to produce the hole, since the person skilled in the art will be familiar with the drilling of a homogenous material.
When the pieces form a stack of different materials, it is usually not possible to easily produce a quality hole with the same tool and/or with the same cutting parameters.
In that case, which occurs for example when drilling through a stack composed of a metal piece and a piece made of composite material, it is known to use a tool considered to be compatible with both materials and to vary the cutting parameters, rotation speed and advance of the drill bit based on the material being drilled.
This solution, however, has the disadvantage of not being possible for all of the pairs of materials encountered in the industry, and when it is possible to use a tool compatible with both materials, the choice is often the result of a compromise on the drilling conditions and quickly leads to damage to the tools, due to the conditions under which they are used. This results in drill holes whose quality, particularly the surface condition of the hole, is lower than that obtained when drilling with optimized tools.
It is also known to drill through each layer with a suitable drill bit, which requires drilling the hole in several stages, changing the drilling tool each time the material being passed through changes.
This solution leads to increased production times, and stopping and restarting the drilling after each tool change can lead to defects in alignment as well as defects in the surface condition of the hole.
These known solutions are even more difficult to implement when the different materials passed through are materials that have relatively incompatible drilling requirements due to their intrinsic characteristics, for example in the case of a stack comprising a piece made from a titanium alloy and a piece made from a carbon fiber composite material.